The present application relates to a method and apparatus for processing data. In particular, the present application relates to a method and apparatus for processing images.
The Film Industry, almost since its inception over 100 years ago, has produced films in almost the same way. This involves substantial photo-chemical work. However, recently there have been advances in the ‘Digital Film Lab’. In this mode, it is often desirable to digitise all of the ‘Camera Original’ material, and edit, grade, and add effects in the digital domain. When a final version is agreed on, it is then usual to ‘write’ this material back onto a (new) film. This technique is often referred to as ‘Digital Intermediate’, or ‘DI’.
To perform techniques of the above type at a resolution that looks like the conventional film, it is necessary to work at resolutions of typically 2048 pixels by 1556 lines per frame. Cinematographic Film requires 24 frames per second to maintain fidelity in motion. Resolutions of 3000×2200 or even 4000×3000 are not uncommon.
One of the many applications that is required to be performed on the data is referred to as ‘grading’. This involves altering the ‘look’ of the material. This in turn consists of many adjustments to be made to the data. One such adjustment is altering the overall ‘lightness’ or ‘darkness’ of the material. Another consists of altering the colour reproduction. This may be an overall colour reproduction change, for example making the overall scene ‘redder’ or ‘bluer, or it may be only for a certain range of colours.
To be able to handle files of the image data, whose total capacity can be in the Terabyte range, and to be able to process film frames in ‘real time’ (i.e. at 24 frames per second) it is generally necessary to utilise powerful computers with substantial amounts of disc space. Such computers are necessarily expensive. Alternatives exist, typically on lower end PC style computers, with processing of frames being in ‘non-real time’. However users report frustrations at not being able to see the processed image in real time.
It is desirable to utilise industry standard computer components wherever possible. Currently available personal computer graphics cards offer substantial processing power, and yet because they are sold worldwide in quantities of many hundreds of thousands, are relatively cheap. However, it is not possible to concatenate the output of several of these cards, as each one runs at a slightly different frequency. Whilst in practice, if several of these cards are feeding several computer monitors, the slight frequency difference may result in the positioning of the image in a slightly different position on each monitor, this positioning error would not be noticeable. However, when we are trying to simulate a complete display that is composed of the output of several video cards, then this would be highly objectionable.
Whilst it is possible to purchase specialist graphics cards which have a ‘Genlock’ facility whereby the graphics cards operate at a frequency fixed by an external source (i.e. the external signal replaces an internal clock for the graphics card), these cards are considerably more expensive than PC Graphics cards which do not have this functionality. It is therefore desirable to find another solution that is not as expensive as this Genlock option.
The present invention, at least in preferred embodiments, sets out to address at least some of the above-mentioned problems with current systems.